
Are you even reading properly? They're not siblings at all. They also never grew up close with each other. I'll help you, try to figure out this picture.
https://www.mangago.zone/read-manga/doku_wo_kurawaba_sara_made/uu/br_chapter-218853/pg-8/

Yeah I'm with you in this one... I really hate the plot siblings to lovers. Even if blood related. It's majorly disrespectful to people like me who have adopted siblings and to people that have step family and never saw them romantically as well.
My major problem with that is the same with romancizing grape and abuse. While it is fiction when it becomes too common it starts reflecting in reality. Media is a powerful weapon. And some time ago we had a massive trend of this legal but not blood related siblings to lovers stories popping up.
Also. It bothers me that step-family/adopted "romantic" relations started in corn after they were forbidden to portray incest and needed a "legal alternative". False incest is a very popular niche there. I don't like seeing that in romance tbh.
I only accept these two because... there's no one else less worse than him to be with her... ╮( ̄▽ ̄)╭
Call me messed up and all but I wish Juliette and Sigurd to be couples.